HYROX is unlike anything else in endurance sport. You are not running a marathon. You are not doing a CrossFit competition. You are doing both simultaneously, and your nutrition needs to reflect that.
Finish in under 60 minutes and you will barely touch your glycogen stores. Push into 90 minutes, 2 hours, or beyond, and you will hit a wall that no amount of mental toughness can overcome without the right fuel in your system. The mistake most HYROX athletes make is not in training. It is showing up with a vague plan, a gel jammed in a pocket, maybe a banana before the race, and hoping that is enough.
It rarely is. This guide covers exactly what to eat and drink in the 24 hours before your race, what to take during it, how to recover after it, and why each recommendation is grounded in peer-reviewed sports science.
Why HYROX Has Unique Fueling Demands
The Hybrid Energy System Problem
HYROX is structured as 8km of running broken into 1km segments, each followed by a functional fitness station: ski erg, sled push, burpee broad jumps, rowing, farmers carry, sandbag lunges, wall balls. This constant cycling between aerobic running and anaerobic/neuromuscular power output creates a specific physiological challenge.
Running primarily uses aerobic glycolysis, a relatively efficient system that burns glycogen and fat. The stations spike toward anaerobic energy systems, depleting muscle glycogen at a dramatically faster rate. Research on high-intensity intermittent exercise shows glycogen utilisation during repeated maximal efforts can be 2 to 3 times higher per unit time than during steady-state running of equivalent duration (Hargreaves et al., 2020).
The practical implication: even athletes finishing in 70 to 80 minutes can be working from a meaningfully depleted glycogen baseline by the final stations if they have not fueled correctly in the 24 hours prior.
Those repeated station efforts are also heavily phosphocreatine-dependent. For athletes who want to support repeat power output across training blocks, creatine monohydrate is the most researched compound in sports nutrition for that purpose. See our guide to creatine for endurance athletes.
The Electrolyte Problem
HYROX events are typically held in large indoor venues. Humidity varies, temperature is often higher than outdoor racing, and there is no wind to aid cooling. Sweat rates for HYROX athletes are significant, generally 0.8 to 1.5 litres per hour.
Sodium is the dominant electrolyte lost in sweat, at concentrations averaging 800 to 1,000mg per litre in trained athletes (Shirreffs & Sawka, 2011). At a 90-minute race with a sweat rate of 1 litre per hour, that is 1,200 to 1,500mg of sodium lost.
Pre-Race Nutrition: The 24 Hours Before HYROX
48 Hours Out: Begin Carbohydrate Loading
For races expected to last longer than 60 minutes, carbohydrate loading in the 24 to 48 hours prior is one of the most evidence-based performance interventions in sports nutrition. A meta-analysis published in the Journal of Sports Sciences found that carb loading increases muscle glycogen concentration by 20 to 40%, which directly delays fatigue onset in events lasting 90 minutes or more (Hawley et al., 1997). See our deep-dive on carb loading for HYROX.
Carbohydrate target: 7 to 10g per kilogram of body weight in the 24 hours before race day.
The Night Before
Keep dinner simple. A meal you have eaten dozens of times before. 250 to 300g cooked pasta with simple tomato sauce, 100 to 150g lean protein, small serve of well-cooked vegetables. Water with electrolytes throughout the evening. Avoid alcohol entirely — even one to two drinks impairs glycogen synthesis by up to 50% (Burke et al., 2003).
Race Morning
3 to 4 hours before: 1 to 2g carbohydrate per kg bodyweight. Oats with banana and honey, white toast with jam, rice with eggs.
30 to 60 minutes before: Small fast-digesting top-up: 30 to 40g carbs. A banana, 2 rice cakes with honey, or one serve of HYDRAX PRIMER in 300 to 500ml of water, taken 25 to 40 minutes before your race. PRIMER is the HYDRAX system's pre-session product. 29g of dual-carb fuel, 1,313mg of sodium, and 5,600mg of sodium citrate. No stimulants. No caffeine. Just carbohydrate availability and sodium loaded into your system before the first drop of sweat. It is built specifically for the problem of blowing up early, the rep 3 feeling that shows up before you have even found your rhythm.
Take PRIMER before. Take CORE during.
During the Race: Do You Need to Fuel?
Under 60 Minutes: Electrolytes Over Carbs
If you are finishing under 60 minutes, your pre-loaded glycogen stores will see you through. What you do need is sodium. Pre-loading 500 to 1,000mg sodium in the 45 to 60 minutes before the race is more useful than anything you can consume during it. Recommendation: one serve of HYDRAX PRIMER 25 to 40 minutes before the race. See fueling by race duration.
60 to 90 Minutes: Optional But Beneficial
A 500ml bottle of HYDRAX CORE (approximately 60g carbs, high-sodium electrolytes) carried on a race belt. Take 2 to 3 sips in transition zones between your 4th and 5th run segments.
90 Minutes Plus: Non-Negotiable Fueling
Target: 40 to 60g of carbohydrate per hour, beginning from approximately 40 to 45 minutes into the race. The dual-carb formulation in HYDRAX CORE (maltodextrin + fructose) is specifically engineered for this scenario. When carbohydrate consumption exceeds 60g per hour, a single-carbohydrate source saturates SGLT1; adding fructose, which uses GLUT5, lifts total absorption to 90 to 120g per hour (Jentjens & Jeukendrup, 2005). The full mechanism is explained in why dual-carb fueling works.
Built for hybrid racing
HYDRAX CORE — Dual-Carb Race Fuel
The in-race half of this protocol in one bottle. Engineered for the 40 to 60g per hour target above, with a sodium load that holds up at HYROX intensities.
- 2:1 maltodextrin to fructose for absorption beyond the SGLT1 ceiling
- 980mg sodium per serve to match high sweat-sodium losses
- Low osmolality so it clears the stomach under load
Electrolytes: The Most Underestimated Variable
Sodium is lost in sweat at 400 to 1,500mg per litre depending on the individual, a range so wide that blanket advice is nearly useless (Baker, 2017). What is consistent is that sodium depletion at HYROX intensities leads to measurable reductions in force output, increased cramping, impaired cognitive function, and in athletes who drink excessive plain water without electrolytes, hyponatraemia. For product-level guidance, read our take on the best electrolyte for HYROX.
Signs you may be a high sodium loser:
- Visible white salt rings on skin or kit after training sessions lasting 60-plus minutes
- Muscle cramps during or after intense sessions
- Strong cravings for salty food after long or hard training
- Headaches following long or intense sessions
| Race Duration | Sodium Strategy |
|---|---|
| Under 60 min | Pre-load 500mg sodium; no in-race electrolytes needed |
| 60 to 90 min | Pre-load 500 to 750mg; sip HYDRAX CORE if carrying a bottle |
| 90 min plus | Pre-load 750 to 1,000mg; consume 200 to 300mg sodium per 500ml fluid in-race |
Post-Race Recovery Nutrition
The 60 to 90 minutes following your HYROX is the most critical nutritional window of race day. Glycogen resynthesis is fastest immediately after exercise. Research shows muscle glycogen can be replenished at 5 to 7% per hour in the first two hours post-exercise when carbohydrate is available (Ivy et al., 1988).
Carbohydrates: 1 to 1.2g per kg in the first hour post-race. For a 70kg athlete: 70 to 84g.
Protein: 25 to 40g of high-quality protein to stimulate muscle protein synthesis (Moore et al., 2009).
Sodium and fluid: Replace 150% of fluid losses over the 2 to 4 hours post-race.
Immediate post-race: A full serving of HYDRAX CORE in 500ml water delivers fast-absorbing dual carbs and sodium for rapid rehydration. Follow with a whole food meal within 90 minutes.
Between races and through training blocks: Daily HYDRAX CREATINE at 5g supports repeat power output across the stations and helps maintain lean mass through heavy HYROX training. It is unflavoured, so it stacks with your existing routine without changing anything else.
HYDRAX CREATINE — 100% micronised creatine monohydrate. 5g clinical dose. Unflavoured. Built for hybrid athletes.
Shop HYDRAX CREATINERace Week Nutrition Planner
| Timing | Goal | Action |
|---|---|---|
| 48 hrs out | Begin glycogen loading | 7 to 8g carb/kg, reduce fibre and fat |
| 24 hrs out | Maximise glycogen | 8 to 10g carb/kg, light session only |
| Night before | Final top-up | High-carb dinner, no alcohol, no new foods |
| Race morning (3 to 4 hrs) | Restore liver glycogen | 1 to 2g carb/kg, familiar food only |
| 30 to 45 min before | Top-up + electrolyte load | Half HYDRAX CORE in 400ml water |
| During (under 60 min) | Maintain electrolytes | Pre-load only; no in-race fuel |
| During (60 to 90 min) | Light carb + electrolytes | Sip HYDRAX CORE from around 45 min |
| During (90 min plus) | Active carb replacement | 40 to 60g carb/hr via HYDRAX CORE |
| Post-race (within 30 min) | Kickstart recovery | Full HYDRAX CORE + protein |
| Post-race (within 90 min) | Recovery meal | High-carb, protein-rich whole food meal |
Built for hybrid racing
HYDRAX CORE — Dual-Carb Race Fuel
The in-race half of this protocol in one bottle. Engineered for the 40 to 60g per hour target above, with a sodium load that holds up at HYROX intensities.
- 2:1 maltodextrin to fructose for absorption beyond the SGLT1 ceiling
- 980mg sodium per serve to match high sweat-sodium losses
- Low osmolality so it clears the stomach under load
HYDRAX PRIMER — Pre-session fuel. 29g dual-carb, 1,313mg sodium. Take it 25 to 40 minutes before. Then go.
Shop HYDRAX PRIMERThe 5 Most Common HYROX Nutrition Mistakes
1. Treating caffeine as a fuel source. Caffeine (3 to 6mg/kg, 60 min pre-race) is an effective ergogenic. It does not replace glycogen.
2. Drinking only plain water during the event. Consuming large volumes of plain water during a 90-plus minute event without electrolytes dilutes plasma sodium and increases cramping risk.
3. Eating a large meal within 90 minutes of the race. Solid food takes 2 to 4 hours to clear the stomach at rest, and longer under competitive stress.
4. Using race day as an experiment. Never consume a product on race day that you have not tested in training.
5. Arriving dehydrated. Starting any event dehydrated means performance is already compromised before the first station.
Frequently Asked Questions
Do I need to fuel during HYROX if I finish under 60 minutes?
Generally no. Focus on sodium pre-loading rather than in-race carbohydrates. A half-serving of HYDRAX CORE 30 to 45 minutes before the race handles both.
What is the best thing to eat the night before HYROX?
A high-carbohydrate, low-fat, low-fibre meal you have eaten many times before. White pasta with tomato sauce or rice with lean protein are both excellent choices.
Can I use energy gels during HYROX?
Yes, but they are logistically difficult. A HYDRAX CORE bottle is more practical for most athletes.
Should I carb load for HYROX?
If you are finishing under 60 minutes, evidence is limited. For athletes targeting 75-plus minutes, carb loading in the 24 to 48 hours prior meaningfully increases muscle glycogen and delays fatigue.
How do I know if I am a heavy sodium sweater?
Look for white salt rings on your kit after training, frequent muscle cramps, and strong post-session salt cravings.
References
Hargreaves M et al. (2020). Nature Metabolism. | Shirreffs SM & Sawka MN (2011). Journal of Sports Sciences. | Hawley JA et al. (1997). Journal of Sports Sciences. | Jentjens RL & Jeukendrup AE (2005). British Journal of Nutrition. | Burke LM et al. (2003). Journal of Applied Physiology. | Baker LB (2017). Sports Medicine. | Ivy JL et al. (1988). Journal of Applied Physiology. | Moore DR et al. (2009). American Journal of Clinical Nutrition.
Disclaimer: This article is general information only and is not medical, nutritional, or health advice. It does not take your individual circumstances, health status, medication, or training history into account, and no therapeutic outcome is claimed or implied. Nutrition needs vary between individuals. Consult an accredited sports dietitian, your doctor, or another qualified health professional before making changes to your nutrition, hydration, or supplementation.